A Light Emitting Device (LED) is a semiconductor device converting current into light. Beginning with a commercialized red LED, red and green LEDs are used as a light source of an electron device including an information communication device.
For example, a Gallium Nitride (GaN) semiconductor has a high thermal stability and wide bandgap, and also is combined with other elements such as In, Al, etc. to manufacture a semiconductor layer for emitting green, blue, and white color lights. Additionally, because emission wavelength is easily controlled, the GaN semiconductor attracts considerable attention from high-output electron device development fields including an LED.
However, the reason that the GaN semiconductor growth has more difficulties than other group III-V compound semiconductors is that there is no high-quality substrate, for example, a wafer including materials such as GaN, InN, and AlN.
Accordingly, when an LED structure grows on a heterogeneous substrate like sapphire, defects occur frequently and thus affect the LED performance.